This invention is concerned with the cutting of materials by means of a focused laser beam.
As a heat source, a laser beam permits an energy concentration of exceedingly high order and for some years, the laser has been known as a piercing instrument where fine holes are required and as a cutting instrument for relatively thin workpieces. A laser beam can be focused to a small spot with considerable accuracy and CW lasers are now commercially available which can deliver energy (10 kW and above) to a workpiece at a rate sufficient to boil or evaporate the workpiece material in its path to provide a cutting process. Consequently the laser has been considered as an out-of-vacuum cutting instrument for many materials and to make narrow cuts in such materials as would not be possible with conventional cutting methods.
Heretofore it has been discovered that if a jet of gas which produces an exothermic reaction is so directed that it flows onto the region of the workpiece at which a laser beam is focused, not only is there an increase in the rate of cutting, but the accuracy and fineness of the cut are substantially unimpaired by the addition of the gas stream in spite of the fact that the cross-sectional area of this stream at the workpiece may differ by an order of magnitude from that of the laser beam. The width of such cuts are determined largely by the width of the laser beam and not by the gas jet, which controlled the width of cuts in prior art processes of thermal cutting which utilize an exothermic reaction.
For a more comprehensive discussion of gas assisted laser cutting including various arrangements and orientations of the laser beam and gas jet, reference is made to U.S. Pat. No. 3,597,578.